Process of annealing metal.



JOHN H. BENNETT, OF WORCESTER, MASSACHUSETTS. I

PROCESS OF ANNEALING METAL.

No Drawing.

To all whom it may concern:

Be it known that I, JOHN H. BENNETT, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Process of Annealing Metal, of which the following is a specification.

This invention relates to a process of annealing soft or low carbon steel by which new and most desirable results are attained. WVhile capable of general application, the invention relates particularly to the treatment of metals which have been hardened by the action of dies as in punching, pressing, drawing and forging operations.

As is well known, the hardening of the metal during these operations necessitates frequent annealing or softening of the metal before subsequent operations can be per formed. The usual procedure is to heat the metal to a red heat and to allow the heated metal to cool slowly in air. Such air cooling forms a scale on the metal which frequently necessitates the use of an acid bath or pickle for its removal before further drawing or pressing operations can be performed. The quality of the metal is not improved by this acid bath and in many cases the acid treatment is positively detrimental.

It is the object of my invention to provide an improved process of annealing by the use of which the acid bath may be omitted, while at the same time the annealing is more perfectly performed.

In the carrying out of my invention, the soft or low carbon steel is heated to a red heat as has been the previous practice, but instead of allowing the heated steel to cool in air, the steel is immediately cooled by the application of water to which soap or other saponaceous material has been added. lVhile I do not wish to be limited to any eX- act proportions in the composition of my saponaceous solution, I have found that excellent results may be attained by the use of one ound of soap dissolved in each ten gallons of water. The addition of soap or similar material to the water entirely changes the action of the water upon the steel. If clear water is used, the metal is hardened and becomes so brittle that subsequent drawing operations are not possible. When, however, water containing a soapy material in solution is employed for Specification of Letters Patent.

Patented Dec. 31, 1918.

i Application filed August 14, 1918. Serial No. 249,811.

the cooling bath, the metal thus treated is found to be actually softer than when allowed to cool in air, and furthermore the surface of the steel is clean and free from scale, thus requiring no acid treatment before further operations are performed.

Many important advantages result from the use of this new and improved annealing process. The delays heretofore necessary between successive operations are largely eliminated as the metal can be cooled immediately after the heating operation and is then available for the next succeeding operation, whereas under the old process a delay of from twenty-four to forty-eight hours was caused by the necessity for slow air cooling and subsequent acid treatment. The presence of large quantities of red hot metal slowly cooling in the air is very objectionable in the heated season, and the space occupied by such metal is also objec tionable in many cases. An additional fire risk is also created by this air cooling operation. Both time and space are saved by my new process, and the comfort of the operatives is increased.

While I have described my process as particularly applicable to articles which must be heated for annealing, it is also applicable to articles which are forged hot and which therefore do not require the separate heating after the forging operation. Such articles may be plunged immediately into a bath of soapy water and are then ready for the next operation.

While I have herein described the steel as being placed in a bath of soapy water, it will be understood that the water may be applied to the metal in any convenient manner as by a stream or spray, as well as by immersing the metal in the water, although the latter procedure is usually preferable.

While I have found a solution of soap in water to be very effective in the carrying out of my improved process. I do not Wish to be limited to this particular solution as other substances of a saponaceous character may be used with satisfactory results. Furthermore, I do not wish to be limited to the details herein described otherwise than as set forth in the claims, and what I claim is 1. The process of annealing low carbon steel which consists in heating the steel and thereafter cooling and softening said steel 3. The process of annealing low carbon by the application of Water to which a steelwhich consists in heating said steel and 10 saponaceous material has en add'edthereafter subjecting the steel to the cooling 2- The pro ess f anne g 10W Carbon and softening action of soapy Water. steel Which COHSlStS lnlleal'flllg Said; Sill- Ifitestijno'ny whereof have hereuntg 3fthereafter placing said steel in abath of fi d my i tur Water containing a saponace'ous material in solution. I JOHN H. BENNETT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

1 Washington, D. 0." 

